How does an elimination of number and letter grades throughout the year (with the exception of quarter and semester grades) affect student attitudes toward learning?

1. How does an elimination of number and letter grades throughout the year (with the exception of quarter and semester grades) affect student
attitudes toward learning?
2. How does an elimination of number and letter grades throughout the year (with the exception of quarter and semester grades) affect our
teaching styles, use of assessments, and choice of curriculum materials?
3. How does an extensive use of student self-assessment affect student growth, improvement, and achievement over the course of a school
year?
4. How does deemphasizing grades allow us to enrich our teaching?